Die assembly and rubber insert for flanging sheet metal



Patented Sept. 14, 1948 UNITED STATES i/ATENT OFFICE DIE ASSEMBLY AND RUBBER INSERT FOR FLANGING SHEET METAL u Amical A. Timmons, McKinney, Tex., assigner of ninety-eight per cent to Wayde Timmons, Mc-

Kinney, Tex.

Application June 28, 1,944, Serial No. 542,519

` Claims. 1

This invention relates to metal working tool return flange many difficulties have been encountered in turning this flange and particularly in forming-the operation without rippling or wrmkling the metal and to provide against disalignment of the return flange. The only method known, wherein apart of this particular design has been satisfactorily produced is that in which the part is rudimentarily formed on a die of a hydraulic press of the type having an overhead rubber platen, with the return flange disposed at an obtuse angle with respect to the Vmain body of the part when the press operation has been completed. The part is then removed from the press and the unfinished flange is hammered into a po- 'I sition at the required 90 with respect to the main body of the part. Not only is this an expensive procedure from the standpoint of production but in order to satisfactorily form the part by this process, it has been the practice to use soft or annealed temper material, due to its malleabllity and minimum spring-back, and after forming, the part is hardened, which further adds to the cost of production.

It is the principal object of the present invention to provide a die particularly adapted for use on hydraulic presses having rubber platens, for forming return flanges on sheet metal parts and which die is to be employed in conjunction with or auxiliary to conventional dies heretofore used for initially forming the part carrying the return flange. The die -of the invention. or yplunger as it may be referred to, is in the form of a rubber block adapted to be placed under the partially formed return flange of the part as the ilrst step of the second and last operation and forced under the lip of the female die of the conventional die assembly by a wedge. propelled into position by the rubber platen of the hydraulic press. When the operation is completed. the return flange will have been formed and the part completed.

With the foregoing objects as paramount, other objects will become apparent in the course of the following description, as well as certain features of accomplishment.

In the drawings:

Figure 1 is a vertical sectional view of a die assembly, including that of the invention, disposed on the bed plate of a hydraulic press` t I Figure 2 is vertical sectional view showing the y dies in operative position in the forming of the return flange, and

Figurev 3 is a perspective view of the part with the return flange.

Continuing with a more detailed description of the drawing. reference is primarily made to Figure 3 wherein is shown a part used in the construction of airplanes, consisting of the main body I0, having a right angle flange II at one end and a return flange I2 at the other.

In Figure 1 is shown in part the head I 3 'of a hydraulic press, carrying a rubber platen I I. Below the head is a bed I5 on which rests the die I6 of the assembly and complementary wedge die I1. The die I6 is of conventional design except` for minor variations to be described later and has been long used for partially forming the part in the manner shown in Figure 1.

The die I6 is formed with an inclined surface a at one end while the opposite end is undercut to define a flange recess I8. the top of which is inclined at b. The degree ofinclination of the surfaces a and b is calculated in accordance with the amount of spring-back of the particular type of material used in making the part. For example, if the spring-back of the part is expected to be 4 degrees, then the surfaces a and b will be offset a corresponding number of degrees so that all angles will be on the part shown..

In ordinary practice, the recess I8 is so formed that the top thereof will be parallel to the top of `the die I6 since there would be no object in providing the inclined surface b, as will become manifest presently. A sheet metal blank cut to the desired dimensions is simply placed on the die I 6 and a block I9 disposed thereon. As the platen I4 is brought into position on the assembly, the rubber will flow thereover and depress the ends of the blank downwardly against the inclined ends of the die and the longest lof the two ends will be thrust into the recess I B in the die I6. However, in practice, the rubber of the platen I4 will not flow into the recess to a depth sufficient to form an angle of 90 on the part. although exhaustive experiments have been carried out with an effort to bring this about. The only compromise has been to shape the part in the manner shown in Figure 1 and complete the flange I2 on another machine as a final operation.

The present invention provides a rubber plunger or insert 20, the required size :and shape of which is determined by the shape of the die or part and the amount of the cubic content of the v ently. Of course. the rubber insert need not necessarily be the same type or density as that of the platen of the press; it may vary to suit the need or the type of material available or desired. In the case of metals with greater thicknessees than those commonly used, the cubic content of the rubber insert or plunger 20 may be increased so that there will be enough pressure or compaction in the insert to form the part,

To form the return flange in accordance with the invention, the first operation necessary to break the ends of the blank is performed in the manner earlier described with the wedge i1 removed. The rubber insert or plunger 20 is then placed as Ashown in Figure 1, with the wedge i1 in juxtapositionecl relationship thereto, after which the operation is repeated, that is to say, the platen i4 is brought down upon the assembly so that the nubber of the platen wm, in flow-l ing in all directions with equal density, bear upon the arouated surface c of member Il to thrust this member against the insert 20, causing the latter to contract in width but expand in height to rise against and urge the flange i2 upwardly .against the top of the recess I8. Obviously, the rubber of the insertl will completely ll the recess IB and will bear against the flange i2 with great force. Of course, the area c of the wedge il must be sulcient to overcome the resistance of the rubber insert 20 for optimum results and' the die I6 must be constructed to counteract any special pressures to which lt may be subjected. Also, while not'shown in the drawing, which is more or less schematic, provision must be made at the ends of recess i8 to close the same against emergence of the rubber of the insert 20 when the latter is compressed. Small wedges, not unlike the wedge i1 in general form may be used for this purpose.

It is apparent that the Wedge il which compresses the plunger or insert 20 in forming the return flange should be constructed or worked to the mold'line of the part with the degree of spring-back' necessary. Also, provision is made to insure proper guidance of the wedgell such as by a groove 2| in the bed i5 so that the mold line will always be directly opposite the corresponding points on the die line. This feature of the wedge merely helps to form the main flange and to hold the part in place. However, the backing block I9 in most cases will do this.

Obviously, a metal part with a return flange, as shown, can be quickly and accurately produced and from hard material if desired, without the necessity for transferring it from the press to another machine for completion, thus effecting a considera-ble saving in time and labor in mass production of parts of this character. It is likewise possible to employ mechanism other than the hydro-press, to actuate the die assemconditions warrant.

, 4 the scope and meaning of the claims is also considered to be within the spirit and intent of the invention.

What is claimed is:

i. In a die assembly for forming a yreturn flange in a sheet metal part under pressure of a rubber platen, a forming block having inclined ends,.one of the ends being recessed to delinea ledge having an inclined undersurface, partially forming a flange' on said part in the primary operation of said platen, a rubber body of greater content than that of said recess, insertabie under said partially formed flange subsequent to the primary operation of said platen, and a wedge in juxtapositioned relation to said rubber body and constrained, under the influence of said platen in a secondary operation, to compress said body to nil said recess and thrust the partially formedl flange upwardly against the inclined undersurface of said ledge to complete said return flange.

2. A die assembly for forming a return flange on a work sheet in combination with a bed and platen of a hydraulic press a forming block undercut at one end, dening a ledge having an inclined undersurface and partially forming a flange on said work sheet in the'primary operation oi' said platen, a rubber block insertable under the partly turned flange of said work sheet subsequent to the primary operation of said platen, a wedge compelled upon downward movement of said platen during its secondary operation to advance upon said rubber block and force the same upwardly under said ledge to flll said undercut and thrust the partly turned end of said work sheet against the undersurface of said ledge counter to the operating stroke of said platen.

3. In combination with a hydraulic press having a vertically movable rubber platen, a die assembly for forming a return flange on a sheet metal part, including a forming block having an overhanging ledge at one end provided with an inclined undersurface by which is partially formed a return flange on one end of said metal part in the primary operation of said platen, a rubber body adapted to fill the space below said ledge subsequent to the primary operation of said platen a wedge movable by said platen in the secondary operation thereof to compress said rubber body to fill said space and to press said partially formed ilange upwardly against the undersurface of said ledge to complete said return ilange.

4. A return flange forming device for use on a hydraulic press equipped with a platen of yieldable and flowable material conforming vto the contour of a work piece, a forming member of non-yielding material having an overhanging ledge the latter provided with an upwardly receding undersurface on which a return flange is partially formed on said work piece in the primary operation of said platen, a plunger of yielding material adapted to underlie the ledge of said forming member subsequent to said primary operation, a member of non-yielding material constrained by said platen on its secondary operation to advance upon and compress said plunger to ll the space below said ledge and upwardly against its receding undersurface to effect con formation of the work thereto, to complete said Y vreturn flange.

Manifestly, the construction asshown and de-` scribed is capable of scmemodiilcation and such modification as may be construed to fell Within.

5. Oomplementary die elements for forming return flange on a work sheet, in combination cluding a forming `element of non-yielding material supporting the work and recessed at one end to denne an overhangirlgd ledge having an upwardly receding undersurtace for underturning an end of the Work in the primary operation of said platen, means composed of yieldable material insertable beneath the undertumed end of said work preliminary to renewed operation of said platen. and means constrained by said platen in its secondary operation to advance laterally against said latter means to compress the same to tlll the void below said ledge and exert pressure upwardly against the underturned end or said work counter to the operative pressure imposed by said platen to complete said ange.

Amar. A. 'rrMMoNs.

6 REFERENCES CITED The following references are of record in the ie of this patent:

UNITED STATES PATENTS 'France Jan. s, wasv 

